1, 4, 7‐Triazacyclononane‐Based Bifunctional Picolinate Ligands for Efficient Copper Complexation. Issue 18 (11th May 2017)

• Record Type: Journal Article
• Authors: Guillou, Amaury; Lima, Luís M. P.; Roger, Mélissa; Esteban‐Gómez, David; Delgado, Rita; Platas‐Iglesias, Carlos; Patinec, Véronique; Tripier, Raphaël
• Is Part Of: European journal of inorganic chemistry. Issue 18(2017)
• Page Start: 2435
• Page End: 2443
• Publication Date: 2017-05-11
• Subjects: Copper -- Macrocyclic ligands -- N ligands -- Imaging agents -- Potentiometry; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201700176
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Three 1, 4, 7‐triazacyclononane‐based (tacn‐based) ligands containing picolyl and picolinate pendant arms (no3py, no2pa1py, and no3pa) were synthesized, and their copper(II) complexation properties were studied to evaluate their potentials as chelators for copper radioisotopes. The thermodynamic stability constants of the complexes were determined by potentiometric titrations. These studies evidenced the formation of mononuclear species for no3py and mono‐ and dinuclear species for no2pa1py and no3pa. The pCu values decreased as the number of carboxypicolyl arms increased. The [Cu(no3py)] 2+ complex presented a very high stability constant (log K CuL = 27.4) and a very high selectivity towards Zn 2+ ions (log K ZnL = 17.25). Vis/NIR (NIR = near‐infrared) absorption and electron paramagnetic resonance (EPR) spectroscopy indicated that the three complexes present distorted octahedral geometries with two paramagnetic species, which were identified as the Δ(δδδ) and Λ(δδδ) isomers [and their corresponding enantiomeric forms Λ(λλλ) and Δ(λλλ)] by DFT calculations. The electrochemical properties were investigated by cyclic voltammetry, which revealed quasireversible behavior for the [Cu(no3py)] 2+ complex but irreversible Cu 2+ /Cu + systems for [Cu(no2pa1py)] and [Cu(no3pa)] – . Abstract : A family of 1, 4, 7‐triazacyclononane‐based (tacn‐based) ligands is developed to find new chelators with improved properties for application as copper(II) radiopharmaceuticals.